Darren Clarke may be forced to withdraw from the Masters with a groin injury.
Having completed nine holes of practice earlier today, the Open champion described himself as "sore".
"I don't think another nine holes is going to do it any good," he told reporters.
The 43-year-old first struggled with the problem at the Houston Open last Friday and as a result missed the halfway cut.
Clarke is due to tee off tomorrow alongside Fred Couples and Ryo Ishikawa.
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